Istio ingress TLS termination

We are trying to access an microservice through istio ingress gateway, the ingress terminates the https connection to http, the job of the microservice is just to redirect the url and send the response. for example if the url is https://google.com the job of the microservice is to add https://google.com/service which actually serves the frontend. But because of istio is terminating the https connection to http, the microservice is redirecting the traffic as http://google.com/service and since there is no webiste like this our connections are failing with 404. Is there a way istio ingress can add back the https while sending the connection back

I think this is possible. In you Gateway spec you can set the mode in Server.TLSOptions to PASSTHROUGH. Make sure your service is loaded with the correct tls certificates

For reference: https://istio.io/docs/reference/config/networking/gateway/#Server-TLSOptions